Air ignition gun



Inventor Ronald Wayne Joyce [56] References Cited $11ringdale,ArkansasUNITED STATES PATENTS Q A- 1968 2,480,100 8/1949 Weiss et al 89/26X e dg Y 3 11970 3,008,258 11 1961 Johnson 42 14 9 1 3,114,290 12/1963 Harveyet al 89/26 Assgnee 3 302 319 2/1967 ROSSelet 89/7X chug, P 3,354,78011/1967 Ramsay 89/26 a corporation of Illinois Primary ExaminerSamuel W.Engle Attorney-Harness, Dickey & Pierce AIR IGNITION GUN 2 Claims, 8Drawing Figs.

U.S. Cl 89/7,

' 89/26, 124/ l 5 ABSTRACT: There is herein disclosed a firearm havingan air Int. Cl F41! 1/04 ignition system for igniting a solid propellantby surface con- Field of Search 124/] l, 13, tact with high temperaturecompressed air and provided with 14, 15; 89/1, 26, 27, 7; 42/l5-22 a newand improved air compression cylinder assembly.

Patentd Nov. 3, 1970 3,537,352

INVENTOR.

/70/71 fig:

. Patented No 3,1970 3,537,352

Sheet 4 of 4 ZFMAM/A/ lym AIR IGNITION GUN PRIOR ART This inventionrelates to improvements in firearms having an ignition system of thetype disclosed in copending U.S. Pat. applications Ser. No. 469,992filed July 7, 1965; Ser. No. 473.556 filed July 7, I965; Ser. No.598,086 filed Nov. 30. I966, now U.S. Pat. No. 3,503,299 Ser. No.598,087 filed Nov. 30, 1966, now US. Pat. Ser. No. 3,399,596; Ser. No.683,029 filed Nov. l4, I967; and issued U.S. Pat. No. 3,302,523. Thedisclosures of the above-identified applications and patent arespecifically incorporated herein by reference.

SUMMARY OF INVENTION The inventive concepts herein disclosed relate to:

1. An air compression cylinder assembly having an obturation-airpassage-valve plug member of new and improved design attached to acompression cylinder in a new and improved manner;

2. Obturation means between relatively movable ammunition holding meansand air compression cylinder means of new and improved design;

3. A trigger-sear assembly of new and improved design;

4. A receiver assembly of new and improved design;

5. A cocking assembly of new and improved design; and

6. A safety assembly of new and improved design.

DRAWINGS An illustrative embodiment of the various inventive concepts isshown in the accompanying drawings in which:

FIG. I is a side elevational view of a rifle type firearm em bodying theinventive features;

FIG. 2 is an enlarged detail view of a portion of the receiver of thefirearm of FIG. 1;

FIG. 3 is an enlarged partial view of the firearm of FIG. I, with partsbroken away, showing the trigger-sear assembly;

FIG. 4 is an enlarged partial view of the firearm of FIG. 1 showing thecylinder head-barrel relationship in the firing position;

FIG. 5 is a partial cross-sectional view taken along the line 5-5 inFIG. 3;

FIG. 6 is a partial side elevational view of the back side of thefirearm shown in FIG. I; 7

FIG. 7 is an enlarged partial view of the firearm of FIG. 1 showing theend cap-compression spring assembly; and

FIG. 8 is an end view of the receiver shown in FIG. 2.

DETAILED DESCRIPTION In General Referring now to FIG. I, there is showna rifle type firearm adapted to fire caseless ammunition ignitable bysurface contact of a solid propellant with high temperature air. Themain working components of the firearm comprise a barrel assembly I0, anair cylinder assembly 12, a piston assembly 13, a trigger-sear assembly14, and a cocking lever assembly 16. A tubular receiver 18, FIGS. 2 and8, is supported on and extends between a front support block 20, towhich it is fixedly attached as by brazing, and a rear support block 22,FIG. 1. The barrel assembly 10 and the front receiver block 20 aremounted on a forearm portion 24 of a wooden stock 26 as by threadedfastening elements 28, 30. The rear support block 22 is secured on thestock 26 by a threaded fastening element 32. A trigger guard 34 isalsoattached to the stock by element 32 and further supported bytransverse pin means 36 which may be solid as shown in FIG. 1 or sleevedas shown in FIG. 3.

Air Cylinder Assembly The cylinder assembly I2, FIGS. 1 and 4, isreciprocably movable and comprises a tubular member 38 of cylindricalcross-sectional configuration fixedly attached to, as by brazing, andclosed at one end by a cylinder head 39 of keyhole cross-sectionalconfiguration and at the other by a relatively movable piston assembly13 to define a variable volume air compression chamber 40 therebetween.Transverse passage means 41 connects the compressing chamber to theatmosphere. A piston cushioning ring 42 having a central air passage 43is mounted on the rear surface of the cylinder head 39. The tubularmember 38 is mounted on a seat 44 of cylindrical cross-sectionalconfiguration against an abutment 45. A lug portion 46 of the cylinderhead extends-through a slot 47 in the bottom of the tubular member 33and carries a transverse pin 48 for attachment to the cocking assembly.A central bore 49 of varying diameter extends axially through thecylinder head 39 and increases in diameter in a forward direction fromcompression chamber 40 toward the rear end of the barrel assembly. Therearwardmost and smallest diameter bore portion 50 is connected to anintermediate and enlarged bore portion 52 by a conical surface 54.Another enlarged bore portion 56 is provided on the barrel side of thecylinder head.

A plug member 57 of generally cylindrical peripheral con- 7 figurationis mounted in bore portions 50, 52, 54 of the cylinder head and hascentral axially extending cylindrical bore portions 58, 60, 62, 64 ofvarying diameter which provide an air passage from the compressionchamber 40. Bore portion 58, next adjacent the air compression chamber,is of smallest diameter and provides an air inlet passage. Bore portion60 is of conical shape and provides a valve seat. Bore portion 62 isol'enlurged diameter to provide a valve chamber 66. Bore portlon 64 isof further enlarged diameter to provide a firing chamber 67 having arelatively thin wall 68 which surrounds the propellant portion of theammunition in the firing position. A ball valve 69 is freely floatinglymounted in the valve chamber 66 and confined therein by a transverse pin70. The diameter of ball valve 69 is such that the ball valve will movefreely to a closed seated position, as shown in FIG. 4, held on theconical valve seat 60 under the influence of pressure forces in thefiring chamber to close the passage 58 and prevent flow of propellantgases and residue to the compression chamber. The ball valve will movefreely to an open position (not shown) under balanced pressureconditions and/or under the influence of pressure forces of compressedair to allow the flow of high temperature air from the compressionchamber to the firing chamber. The outer surface portions 71, 72, 74 ofplug 57 correspond in size and shape to the bore portions 50, 52, 54with cylindrical surface portion 71 of smallest diameter and cylindricalsurface portion 74 of largest diameter connected by a conical surfaceportion 72. Plug 57 is preferably bonded in place in a gas tight mannerby a suitable adhesive to prevent movement of the plug relative to thecylinder and flow of propellant gases therearound. In use of the gun,maximum forces on the plug are exerted rearwardly by propellant gasesagainst conical cylinder head surface 54. A feature of the presentarrangement is that the plug 57 may be relatively easily removed in aforward direction for maintenance and repair or replacement upondisassembly of the A chamber 76 is provided between the outer surfaceportion 74 of the plug and the bore portion 56 in the cylinder head. Thelength of the obturation chamber is approximately the length of the thinwall portion of the plug which surrounds the firing chamber 67. Anannular obturation rim 78 on the rear end of the barrel is adapted to bematingly received in the obturation chamber 76 in the firing positionshown in FIG. 4. The diameter of chamber 76 is about .0015 inch largerthan the diameter of rim 78. The length of the obturation rim is lessthan the length of the obturation chamber 76 so that a substantial gapseparates the rear of the rim from the cylinder head and interferencetherebetween in the firing position is completely eliminated. Axialpositioning of the cylinder relative to the barrel during assembly isdetermined by abutting engagement of a front surface 80 of the cylinderhead 39 in the firing position with a rear surface 82 of the barrelwhich is inserted through bore 83 and positioned, as shown in FIG. 4,protruding rearwardly beyond the rear surface 84 of the front supportblock so as to provide a clearance gap 86. A hole is then drilledthrough housing 20 and barrel l and a pin 87 is inserted to hold thebarrel in the proper position relative to the air cylinder 12.Obturation rim 78 is provided with an annular counterbore 88 having aninside diameter slightly larger than the outside diameter of the frontplug surface 74, 1.0., .001 inch, and ltuving a length slightly longerthan the length of the plug received therewithin to avoid interferenceduring closing movement of the cylinder to the firing position.

An ammunition holding means is provided at the rear of the barrel bore90 adjacent the obturation counterbore by reduced diameter bore portions92, 94 so that a round of ammunition may be inserted through the rear ofthe barrel and held on bore portions 92, 94 with at least a portion ofthe propellant extending rearwardly within the counterbore 88 in theloading position and within the firing chamber 67 in the firingposition.

Thus, when the firearm is in the closed firing position of FIG. 4, theouter annular obturation rim 78 surrounds the firing chamber 67 andextends rearwardly from the ammunition holding means at the rear of thebarrel to a rearwardly facing transverse end surface 95. The rearwardlyfacing abutment surface 82 on the ammunition holding means at the rearof the barrel extends outwardly relative to the outer rim 78 and islocated forwardly of the end surface 95. A first rearwardly openingannular chamber, defined by surface 92, is located within the outer rim78 and terminates in a transverse rearwardly facing end surface 96. Theinner annular obturation rim (:8 surrounds and defines part of thefiring chamber while extending forward from the air compression cylindermeans 12 to a transverse forward end surface 97. The forwardly openingannular obturation chamber 76, defined by outwardly spaced axiallyextending annular surface 56 and a rear forwardly facing surface 98,'islocated outwardly circumjacent the inner rim and matingly receives theouter rim. A second rearwardly opening annular chamber, defined bysurface 88, is located inwardly circumjacent the outer rim in axialalignment with the first rearwardly opening annular chamber 92 andmatingly receives the inner rim. The forwardly facing transverse surface80 on the air compression cylinder means extends outwardly from theobturation chamber 76 and is located forwardly of the transverse surface98 in axial alignment with and adjacent the surface 82. The length ofthe outer rim from surface 82 to surface 95 is less than the length ofobturation chamber 76 so that the surface 95 is axially spaced fromsurface 98 and the inner rim 68 extends within the chamber 88 with endsurface 97 located adjacent end surface 96 of chamber 92. The outsidediameter of the inner rim 68 is slightly less than the inside diameterof the chamber surface 88 so as to provide primary obturationtherebetween and the outside diameter of the outer rim 78 is slightlyless than the inside diameter of the obturation chamber 76 so as toprovide secondary obturation therebetween.

Piston Assembly Referring now to FIG. 1, the piston assembly 13comprises a grooved piston head 100 having a piston expander ringassembly 102 mounted thereon. The piston expander ring assemblycomprises a self-lubricating bronze filled Teflon piston ring ofrectangular cross-sectional configuration and a polyurethane O-ring typeexpander such that no lubrication of the piston is required and sealingis effected between the piston and cylinder during the compressionstroke. Piston head 100 has a stub shaft 104 received in a bore 106 inthe end of piston rod 108 and secured therein by a pin 109. The otherend of rod 108 has a scar notch 110 in a reduced diameter end portion112 which terminates in a scar abutment surface 114. A spring sleeve 116surrounds the piston and defines a spring chamber 118. The rear end ofthe spring sleeve is provided with a necked down portion 120, FIG. 3,fixedly secured in a bore 121 in an abutment plate 122, as by brazing,and providing an abutment shoulder 123 for a compression spring 124having an inside diameter slightly larger than the outside diameter ofthe plunger rod and mounted thereabout in spring chamber 118 between theplunger head and the shoulder 123. The outside diameter of spring 124 isslightly smaller than the inside diameter of the sleeve 116 so that eachradially supports the other with the compression cylinder assembly beingaxially movable both with and relative to the piston assembly along theouter periphery of the fixedly held spring sleeve 116.

Receiver Assembly Referring now to FIGS. 2 and 8, the main receiver 18is shown to comprise a one-piece sheet metal member having keyhole typecross-sectional configuration comprising a partially cylindrical tubularupper portion 126 and spaced depending flange portions 128, 129. Ifdesired reinforcing plates (not shown) may be fixedly attached to thesides of the flange portions. The inner surface 130 of the upper portion126 provides a guide-bore which slidably receives and supports thecylinder assembly 12 for axial movement therewithin between the firingposition of FIG. 1 and a rearwardly spaced loading position (not shown).Slot 131 between the flanges 128, 129 receives the lug 46 and permitsthe cocking lever assembly to be connected thereto. A loading port 134in the upper portion provides access to the ammunition holding means 92,94 at the rear of the barrel when the cylinder assembly is in arearwardly located loading position. A sight mounting plate 137 may bemounted on top of the receiver.

The front of the receiver 18 is supported at the rear of the frontsupport block 20 on and brazed to surface 138, FIG. 4, of correspondingkeyhole configuration against a rearwardly facing shoulder 140. The rearof the receiver is supported by the rear support block 22 on a surface142, FIG. 7 of corresponding keyhole configuration against a forwardlyfacing shoulder 144. Rear support block 22 has an upper rear cap portionwhich provides an exterior surface of the firearm connecting the upperportion of the receiver to the stock. The rear support block also has agenerally U-shaped cavity 146 defined by spaced downwardly depending legportions 147, 148, FIG. 5. A sear slot 149 is formed in the rear wall ofthe cavity. Locating lugs 152 (one on each side of the block), FIG. 7,extend radially outwardly from surface 142 to provide support shoulders153 and extend forwardly of shoulder 144 and surface 142 for engagementwithin opposite rearwardly opening slots 154, 155 in the receiver FIG.8. The upper surface 156 of the lugs is tapered and the front surface157, FIG. 7, is rounded to facilitate a new and improved assembly methodhereinafter described in detail. The abutment plate 122 is centrallypositioned by cylindrical surface 151 which is supportingly mounted onthe forward portion of rear support block as shown in FIG. 5. A pair ofopposite lugs 158. 159 on the forward end of the rear support block havetransverse abutment surfaces 160, 161 which supportingly engagetransverse plate abutment surfaces 162, 163. Plate 122 is furthersupported by inwardly curved abutment surfaces 164, 165 on correspondingcurved portions 166, 167 of the lugs. Plate 122 has a depending lugportion 168 located between opposite walls 169, 170 of the lugs whichare thus held within opposite circumferentially elongated slots 171, 172in the receiver. Slots 171, 172 are located below the longitudinal axisof the tubular portion 126 and extend into the flange portions 128, 129.As may be seen in FIG. 5, the outermost surfaces 174, 175 are locatedapart a distance slightly less than the inside diameter of the tubularportion. Opposite support lugs 176 (there being one on each side), FIG.7, may be provided in the rear support block. The rear support block isprovided with opposite aligned pin holes 178, FIG. 7, for supporting ascar pin 180, FIG. 3. A threaded opening 182, FIG. 7, for fastener 32extends upwardly and slightly forwardly into the cap portion 145 throughan inclined surface 184 which is terminated by transverse surfaces 185.186 located in axially spaced relationship to the adjacent surfaces 187,188 of the stock, FIG. 3. Block 22 is supported on the stock byrearwardly extending surface 190.

The method of assembly comprises fixedly mounting the receiver 18 on thefrom support block 20. Then the cylinder assembly 12 and the pistonassembly 13 are positioned in the forward part of the receiver in thefiring position (not shown). The spring 124 is placed over the pistonrod 108 in an expanded condition. Then the spring sleeve 116 and plate122 attached thereto are positioned on the rear of the expanded spring124 and then moved axially forwardly against spring 124 by a suitabletool or fixture (not shown) to a position where at the rear of the plate122-is located forward of slots 171, 172. The rear support block 22 isthen inserted in a tilted position with surface 192 extendingsubstantially parallel to surface 130 and lugs 158, 159 located alongthe longitudinal axis of the tubular portion. Lugs 158, 159 are movedalong the inner surface 130 of the upper tubular portion 126 until thelugs 158, 159 are aligned with slots 171, 172 at which time lugs 152have entered slots 154, 155. Block 22 is rotated downward to bring lugs158, 159 into engagement with slots 17!. 172, FIG. 5. The spring sleeve116 and plate 122 are then released and moved rcurwurdly by partiallycompressed spring 124 into position against block 22 which engagessurfaces 160, 161, 164, 163, 169, 170 as shown in FIG. 5. Lugs 158, 159are then trapped in slots 171, 172 and thereafter bear against sidesurface 194, FIG. 2, of the slot whereby block 22 is held fixedly inposition without further attaching means.

Trigger-Sear Assembly Referring now to FIG. 3, trigger assembly 14 ispivotally mounted on a pin 204 in a trigger cavity 205 beneath the rearsupport block, between the flange portions 128, 129 of the receiverwhich support the trigger pivot pin 204 in opposite aligned pin holes206 (FIG. 2), and in a slot 208 in trigger housing 34. Trigger housing34 is a one-piece casting suspended at the forward end on transverse pin36 by a forwardly and upwardly extending finger 210 which forms a seat212. Assembly of the trigger housing is effected by forward and upwardsliding movement onto the transverse pin 36 and then rotation thereaboutto seat the rear portion 214 on a seat 216 in the stock. Fastener 32also holds the trigger housing 34 in place.

The trigger assembly 14 comprises a main trigger casting 217 pivotallymounted by a central hub portion 218 on pin 204 for movement between aforward position as shown in FIG. 3 and a rearward release or firingposition (not shown) by application of finger pressure on a dependingfinger lug 219. A side plate portion 220, FIG. 6, of the trigger castingextends radially about one side of hub portion 218. A rim portion 221 ofthe trigger casting extends transversely from the plate portion onopposite sides of the finger lug and forms a cavity 222 in which a searrelease pawl 223, a pawl spring 224, and one end of a trigger-searspring 226 are mounted and retained by a keeper plate 228. Pawl 223 hasa hub portion 230 rotatably supported on the trigger hub 218 andopposite radially extending arms 232, 234. One end of the pawlcompression spring 224 is seated on a lug 236 on arm 232 and the otherend is seated in a spring well 238 formed in a portion 240 of the rim221. The other arm 234 is adapted to abut the end of an adjustable screw242 threadably mounted in a rim portion 244 and normally be heldthereagainst under the influence of pawl spring 224. The purpose of thisscrew is to permit adjustment of the pawl for proper engagement with thesear to compensate for manufacturing tolerances and permitstandardization of trigger pull'characteristics. An inspection hole 245is provided in flange 128 to assist in this adjustment. One end of thetrigger-sear spring 226 is nested in a spring well 246 formed in a rimportion 248. Keeper plate 228 has a hub portion 250 which is pressfitted onto trigger hub 218 and may be staked or otherwise additionallysecured to the rim portion as at 252. Trigger-sear spring 226 biases thetrigger assembly to the forward position, in a clockwise direction asviewed in FIG. 3, bringing an abutment flange 254 on the trigger intoengagement with the bottom of plate 122 at 255. Rearward movement of thetrigger is effected against the bias of the compression spring 226.

A sear 260 is pivotally mounted on pin 180 and has a downwardlyextending lug 262 and spring seat 264 which receive the other end of thetrigger-sear spring 226 to exert a counterclockwise force on the sear. Anotch 266 between spaced lugs 268, 270 receives the end of the pistonrod with lug 268 being located in the rod notch and holding the rod inthe cocked position by abutting engagement at 271. The forward bottompart of the sear extends into the trigger cavity 222 through an upwardlyfacing slot between the side plate 220 and the keeper plate 228. A pawlnotch 272 in the bottom of the sear has a curved upper surface 274 whichcorresponds to the curved end surface of the arm 232 and a transverseside surface 276 which corresponds to the side of the pawl arm 232. Inthe latched position, pawl arm 232 is located in abutting engagementwith sear surfaces 274, 276 which prevents counterclockwise movement ofthe sear. Pawl spring 224 has a strength sufficient to keep the searlatched until the trigger is pulled rcarwardly and the pawl arm 232 ispositively moved out of abutting engagement with sear surfaces 274, 276.Counterclockwise movement of the sear is limited by an abutment surface278 on the rear of the sear and an abutment surface 280 on the rearsupport block.

When the trigger is pulled rearwardly, screw 242 forces the pawl 223 tobe rotated therewith counterclockwise and the arm 232 is moved out ofthe sear notch 272 whereupon the compression spring 124 drives thepiston and piston rod forward causing the sear 260 to be cammeddownwardly counterclockwise to a release position with sear front sidesurface 282 engaging arm rear side surface 284 and rear sear abutmentsurface 278 engaging the support block surface 280. The sear is held inthe fired position by spring 226 until the piston rod is movedrearwardly during a cocking cycle whereupon the rear rod surface 114passes over the depressed front sear lug 268 and engages the frontsurface of rear sear lug 270. The sear is cammed in a clockwisedirection against the bias of the spring 226 causing the front sear lug268 to move upwardly into latching engagement in the rod notch 110 andallowing the pawl arm 232 to move back into blocking engagement with thesear surfaces 274, 276 in the sear notch 272 under the influence of pawlspring 224. Trigger abutment 254 engages the bottom of plate 122 at 255and holds the trigger in the forward cocked position. The relativelymovable trigger casting 217 and pawl 223 are statically balanced andbiased by springs 224, 226 so that, if the gun is bumped, jarred, ordropped in any attitude, there will be no forces actuable upon thetrigger to cause the gun to accidentally discharge.

Safety Assembly Referring now to FIG. 6, trigger safety 290 comprises aslide plate 292 and a keeper plate 294. The slide plate has a mainelongated body portion 296 slidably supported on receiver flange 128 atone end as by trigger pivot pin 204 received in an elongated slot 298,and at the other end as by an integral receiver flange tab 300 receivedin another elongated slot (not shown). A transverse abutment flange 302extends through a slot 304 in the receiver for blocking engagement withtrigger abutment surface 306 in the on position shown in FIG. 6. Keeperplate 294 is made of spring steel material and also mounted on triggerpivot pin 204 at one end and tab 300 by means of a T-shaped slot 308 atthe other end. The base portion 310 of the keeper plate is formed offsetto the finger portion 312 so that, in the assembled position, a springforce is ex-' erted against the safety. integrally formed dimples 313,314 on the keeper plate cooperate with a detent (not shown) on thesafety to hold the safety in the on-off positions. Manual move ment ofthe safety between the on-off positions is effectuated by means of athumb plate 315 on the end of a flange 316 which is outwardly curved toconform to the curvature of the receiver and extends upwardly through aslot (not shown) between the stock and the receiver at the top of thegun. The safety is also automatically movable to the on position duringthe cocking cycle by engagement of the rear edge 317 of the cylinder 12with a flange 318 extending through a slot 319 in the receiver 18 intothe path of movement of the cylinder.

Cocking Assembly Referring again to FIG. 1, the cocking lever assembly16 is mounted in an elongated slot 320 in the bottom of the forearm. Amanually operable actuating lever 322 is channel shaped with a baseportion 324 extending between spaced parallel flange portions 326 (therebeing one on each side). An abutment and handle plate 328 is welded onthe forward end of the lever between the flanged portions. The rear endof the lever is pivoted on pin 36 which extends through aligned holes329, 330 in receiver ear portions 331, 332. The lever flange portions326 are located between the receiver flange portions 331, 332 and arenotched at 334 to accommodate a spacer pin and bushing 336 in the stowedposition. The spacer pin is mounted in opposite aligned openings 338 inthe receiver flanges. A channel-shaped drag link 340 having a baseportion 342 and spaced flange portions 344 is pivotally connected at oneend to the cylinder head by pin 48 extending through link flangeportions 344 and at the other end to lever 322 by a pin 348 extendingthrough lever flange portions 326. A lever latch means is provided by aspring clip 350 mounted on lever base portion 324 and extending upwardlyfor latching engagement with link base portion 342 through a latch slot352. An additional safety feature is provided byan abutment surface 360,FIG. 3, on the rear end of one of the lever flanges 326 which is locatedin blocking relationship to trigger surface 362 on flange 254 wheneverthe cocking lever is not in the stowed position to prevent rearwardmovement of the trigger.

When the cocking lever is moved from the retracted stowed position ofFIG. 1, pivot pin 348 is moved downwardly and rearwardly on an arc aboutpivot 36. The rear end of link 340 is also moved downwardly andrearwardly while the path of movement of the front end of the link isrestricted to a rearwardly direction since pivot pin 48 is attached tothe cylinder assembly and the movement of the cylinder assembly isconfined by the tubular guide portion 130 of the receiver. The cylinderassembly is thus moved rearwardly and pushes the piston assemblyrearwardly from a fired position adjacent the cylinder head to thelatched cocked position of FIG. 1 in latched engagement with the sear ashereinbefore described. The piston spring 124 is simultaneouslycompressed. The cocking lever is then returned to the stowed positionwhich moves the cylinder assembly back to the firing position of FIG. 1and unlocks the trigger for firing. During the final movement of thecocking lever, the latch spring clip 3S0 enters slot 352 and is sprungover the base portion 342 of the link to hold the cocking lever againstthe bottom of the stock at 364.

It is contemplated that the inventive concepts hereinbefore describedmay be variously otherwise embodied and combined without departing fromthe inventive principles involved and intended to be covered by theappended claims, except insofar as limited by the prior art thoseinventive principles rendered obvious thereby.

lclaim:

1. In a firearm having an air ignition system including an aircompression cylinder means and an ammunition holding means relativelymovable between an adjoining location in a firing position and anaxially spaced location in a loading position and having a firingchamber located therebetween in the firing position, the inventioncomprising:

an outer annular obturation rim surrounding the firing chamber andextending rearwardly from said ammunition holding means and terminatingin a rearwardly facing transverse rear end surface; 4

a rearwardly facing abutment surface on said ammunition holding meansextending outwardly of said outer annular obturation rim and locatedforwardly of said rearwardly facing transverse rear end surface;

a first rearwardly opening annular chamber located within said outerannular obturation rim and terminating in a transverse rearwardly facingend surface;

an inner annular obturation rim surrounding the firing chamber andextending forwardly from said air compression cylinder means andterminating in a transverse for ward end surface; forwardly openingannular obturation chamber located outwardly circumjacent said innerannular obturation rim and defined by an outwardly spaced axiallyextending annular surface and a rear forwardly facing transverse surfaceand being axially aligned with and matingly receiving saidouter annularobturation rim in the firing position;

a second rearwardly opening annular chamber located inwardlycircumjacent said outer annular obturation rim and being axially alignedwith said first rearwardly opening annular chamber and matinglyreceiving said inner annular obturation rim in the firing position;

a forwardly facing abutment surface on said air compression cylindermeans extending outwardly of said forwardly opening annular obturationchamber and being located forwardly of said rear forwardly facingtransverse surface and axially aligned and located adjacent saidrearwardly facing abutment surface on said ammunition holding means inthe firing position;

the length of said outer annular obturation rim from said rearwardlyfacing abutment surface to said rearwardly facing transverse rear endsurface being less than the length of said forwardly opening annularobturation chamber from said forwardly facing abutment surface to saidrear forwardly facing transverse surface so that in the firing positionthe rearwardly facing transverse rear end surface is axially spaced fromthe rear forwardly facing transverse surface, said inner annularobturation rim extending within said second rearwardly opening annularchamber, the transverse forward end surface of said inner annularobturating rim being located adjacent the transverse rearwardly facingend surface of said first rearwardly opening annular chamber;

the outside diameter of said inner annular obturation rim being slightlyless than the inside diameter of the second rearwardly opening annularchamber so as to provide primary obturation therebetween; and

the outside diameter of said outer annular obturation rim being slightlyless than the inside diameter of the forwardly opening annularobturation chamber so as to provide secondary obturation therebetween.

2. In a firearm having an air ignition system including an aircompression cylinder and ammunition holding means, the inventioncomprising:

a plug member for connecting said air compression cylinder to saidammunition holding means;

a cylinder head at the front of said compression cylinder;

a bore of varying diameter extending axially through said cylinder head;

said bore having an end portion of smallest width next adjacent the rearof said cylinder head;

an intermediate portion of larger width;

a transversely extending plug seat connecting said end portion to saidintermediate portion;

the outer periphery of said plug member having a first portion ofsmallest width corresponding in size and shape to said first end portionof smallest width of said bore and being mounted therein;

a second portion of larger width corresponding in size and shape to saidintermediate portion of said bore and being mounted therein, atransversely extending abutment connecting said first portion to saidsecond intermediate portion and being seated on said transverselyextending plug seat;

intermediate portion, said plug member extending therewithin and beingradially inwardly spaced therefrom and defining an obturation chambertherebetween.

